GettingFiggy They can do, you do have to keep on top of changing out litter trays and [picking up stray poos. We do it most nights and it's fine. If the hammocks get smelly we swap them out and by the end of the week they can smell but it's not too bad.
Apparently they do deter mice and rats, I can't say I've had any but I am in a basement flat 
I know people who have kept them in garages and sheds and have never had mouse/rat issues though.
You have to have at least a pair, lone rats are usually not happy rats, they need the company of their own kind. We have a lone rat but it is a rare occurrence. With him it is for a variety of reasons, he didn't learn how to socialise with other rats as he was a very small runt and had to be held most of the time to be kept warm in his formative weeks, he has a lot of health issues, is lethargic and he's epileptic so it's just not safe for him to be in with other rats, despite us trying (we had him in with our big boys for three/four weeks before our Alpha, Haku, decided that he wasn't welcome anymore and probably would have killed him had we not intervened). He spends at least 5 hours out 5 days a week, an hour in the morning free-ranging and then lots of cuddles through the day, he takes a lot of work and he's not a 'normal' rat, they'd need a lot more time out if alone. Rats kept in pairs usually need at least an hour out with you or free-ranging a day, they aren't pets that you can just keep in the cage.
I actually prefer the dynamic of a trio or more. We have a trio of girls and will possibly be taking in a rescue next week to make that four.
RE how I came to love them: we wanted a pet, looked at house rabbits and various caged animals, DP came across a forum post that suggested rats because they were like little dogs and I had a google and found various videos like this:
And a month later we got our first two boys from an NFRS breeder
Then we rescued two girls from an MNetter in March last year, one died in August but before she died we got two babies to keep her companion company, loved the dynamic of three so decided to get a third boy and ended up with Ashi in November last year. I'm completely obsessed. I love rats, they're really interesting creatures and each has their own personality. Five of ours are NFRS breeder rats, one a rescue. Our current breeder is amazing, if you're anywhere near Brighton I can highly recommend her if you can get over the phobia! And I'm always happy to introduce mine to people thinking about getting them too :)
I never had an issue with the tails, I never really had an opinion on them before I got rats but I was surprised by how not wormy the tails were once we got the boys, if that makes any sense? They have got very strong tails, I do love the tails now, I find it fascinating how they use them. They also use their tails for temperature regulation, which I think is amazing.
Feel free to PM me if you want to know anything, I am afraid that I can talk forever about rats and divert a conversation